Hi! I am still working on The Bonding, for anyone who follows that. I'm a little stuck and have a Bleach plotbunny running rampant in my head, so I decided to take a break from it for a bit—shouldn't be too long, considering the state of the next chapter.
Anyway, this story is based with the idea that Ichigo either didn't use Mugetsu or didn't suffer from its aftereffect. Somewhat AU, obviously, but I hope you have fun with it, anyway!
It was sudden and completely unexpected—one moment, Kurosaki Ichigo was sitting in class, taking notes, and the next he was doubling over in agony, coughing blood across his desk, his reiatsu skyrocketing.
He fumbled for the badge Ukitake-san had given him, pressing it to his chest between gasping coughs—then he was outside of his human body, which collapsed without a soul to command it.
The pain was there, but significantly less in his soul-form, though his already crushingly powerful reiatsu continued to rise. With a thought, he returned it to the level it was supposed to be upon, beyond the comprehension of any other being in the dimensions he knew, which caused his already alarmed friends to flinch and glance to his Shinigami form, despite knowing that they were the only ones who could see him and it would look odd to everyone else in the room. At least this way, it wouldn't crush them, though if they got any closer—
He shook his head slightly as he felt his power continuing to grow, wild and beyond anything he had ever before experienced. He had to get out of there—fortunately, it was a nice day and the teacher had left a window open. In the harmonic note of combined Shunpo and Sonido, he was gone.
As the ground beneath his feet began to blacken and smolder, Ichigo reached out and tore the air in front of him, creating a Garganta. In moments, he was through the Severed World and in Hueco Mundo, where his growing power wouldn't harm anyone. Even Hollows never bothered him when he had his reiatsu incomprehensible.
Nearly an hour passed and the sand below him slowly began turning to smoke before his power finally stopped growing. It had more than tripled to his own estimation, and he'd already had five times the power of the average Captain.
He took the time to glance around, taking in the circle of blackened sand around him and the fact that he was slowly but surely sinking into the sand he stood on as it disintegrated under his power.
If he returned to the living world now, there was no telling what would happen. He had to figure out how to reign in this new power before anything else.
Between Urahara and his father teaching him how to seal Zangetsu—which, now that he could, he still never did—and his own reiatsu, he thought he could seal away most of this new power.
It took several hours before Ichigo was satisfied that his power was sealed enough to control.
That accomplished, Ichigo felt that he could return to the Living World safely. Still, just to be cautious, he made sure to open his Garganta in the clearing outside Karakura where once Ulquiorra and Yammy had appeared to 'test' him.
Once there, he shifted his reiatsu enough to allow others to sense it and watched the reactions of small wildlife in the area.
Birds took off and squirrels darted up trees, but nothing dropped dead to the ground. Of course, animals always were more spiritually aware than most humans, so it was unlikely he'd get the same reaction from the humans in Karakura. Most were unlikely to even notice his new power.
His friends, on the other hand…
This was going to be interesting.
His first stop was the Urahara Shoten, in hopes that the man would have some answers. It was a fringe benefit that his spiritually aware friends had congregated there. He supposed he could understand why—his departure had been anything but subtle, and his body was probably in the coma ward of the hospital by now.
He waved acknowledgement to his friends before turning his attention to Urahara and the former 12th Captain's serious expression.
"You know what happened." It wasn't a question.
"I have a very strong suspicion," Urahara corrected. "If I'm right… if you hadn't left your body, you would have died—physically, at least. If you hadn't left your classroom…"
"They would have disintegrated, body and soul," Ichigo sighed, "I know. What I want to know is why."
"Ichigo, the dimensions have had the same Spirit King for over a hundred thousand years. He's not gotten directly involved in anything for over half that time. And, a few hours ago…"
Ichigo closed his eyes, knowing what was coming.
"… he gave up his power and died. He left the message that his power would go to his replacement."